According to the American Psychological Association, anxiety is characterized by feelings of tension, worry and irritability along with physical changes like increased blood pressure. Depression is characterized by sadness, a lack of interest in daily activities, weight loss or gain, insomnia or excessive sleeping, lack of energy, inability to concentrate, feelings of worthlessness or excessive guilt, and recurrent thoughts of death or suicide.

Rates of depression and anxiety in people with arthritis-related diseases varies depending on the population, the size of the study, and the measurement tools used. But data show that the rates can be between two- and ten-times greater than the rates of the general population, depending on the type of arthritis.

Studies show that anxiety and depression can lower your pain threshold. And then the chronic pain aggravates your anxiety and depression. Furthermore, people with arthritis and depression tend to have more functional limitations, are less likely to adhere to their treatment regimens, and have increased odds of developing other health problems.

You can find yourself in a never-ending loop of pain, poor health and negative mood. This vicious cycle can significantly change the course and management of your arthritis.

Pain and Depression

Many studies have shown clearly that people with arthritis with the highest pain levels are the most likely to be anxious or depressed. Exactly why higher pain severity is associated with depression is not clear. It seems to be a two-way street.

Pain incites depression. Living with daily pain is physically and emotionally stressful. Chronic stress is known to change your levels of brain and nervous system chemicals. These stress hormones and neurochemicals – like cortisol, serotonin and norepinephrine -- affect your mood, thinking and behavior. Disrupting your body’s balance of these chemicals can bring on depression in some people.

Depression makes pain worse. Depression weakens a person’s ability to deal and cope with pain, says Marina B. Pinheiro, a researcher at the University of Sydney, Australia. “So an individuals’ perception about their condition, for example back pain, might become more negative when compared with individuals who are not depressed.”

Jon T. Giles, MD, an assistant professor of medicine at Columbia University and rheumatologist at New York Presbyterian Hospital in New York City, says “Painful sensations are relayed through the brain in a very complex way, and can be modulated up or down.” Stress, poor sleep, anxiety and depression all influence pain levels, he explains.

Inflammation and Depression

We know that pain and disability are linked to depression in arthritis, but a developing theory is that inflammation also plays a role.

A 2016 study published in The Journal of Clinical Psychiatry reviewed levels of C-reactive protein – a marker of inflammation – in 10,036 people who responded to the National Health and Nutrition Examination Survey. People with symptoms of depression had CRP levels that were 31% higher than those with no depressive symptoms.

“There is a body of literature recognizing depression as an inflammatory state,” explains Patricia Katz, PhD, professor of medicine at University of California San Francisco. “There is a well-documented event called cytokine-induced depression, where cytokines are increased and depression occurs.” Specific cytokines, such as interleukin-1, interleukin-6, and tumor necrosis factor-α, are involved in the pain and inflammation process in arthritis.

Lifestyle and Depression

Having arthritis is painful and exhausting. Inflammation and the fatigue that goes with it further drag you down. Maybe you then add a co-occurring condition like diabetes or a heart condition. If you’re dealing with all of this, the active life you once knew may have gone out the window.

All of these health challenges may cause you to engage less in physical activity, become less social and more isolated, and have worse sleep quality. These negative changes in your lifestyle can increase your pain and dampen your overall mood – bringing on the blues and depression.

No matter exactly what causes depression in people with arthritis, the link is real and potentially life-changing. Treating not only your arthritis but also specifically treating your anxiety or depressionare key to living your fullest life.